Hello All. I have a 1979 P200e, something is wrong with the stator. Bike runs, and all lights come on except the headlight. I have acquired a PX (probably from a Stella but maybe not, it says Ducati on it) stator but the wiring is different. Instead of a double yellow coming off of the stator I now have a red and yellow. Over on MV someone said just hook it up and run a diode in the purple wire so the headlight doesn't blow cause this new stator will put out more power for the headlight. I swapped to a H4 headlight like a Stella or PX so I am not too worried about that since I think the H4 can handle the additional power.

My main concern (other than the bike not starting now) is that the wiring diagrams show the red wire taking a different path and more modern bikes use a 5 pole regulator, which mine does not, it's 4 pole.

How do I rectify these differences to make this stator work with my US model double yellow wiring harness bike?

I prolly posted on the other board. The red-yellow stator will work the same as a yellow-yellow stator.

But it may not put the same amount of power out.

Over the last couple of weeks I really tested out the best way to make DC with the stuff I had in the garage.

Through this experimentation I am a recent convert to using the GY6 type rectifiers and regulators. I have a 6 volt one for my rally 200 and it works great and only takes one AC input to make it work. It puts out both regulated AC for and DC at 6 volts. There are other ones available for 12 volt (which are easier to get). I plan to buy a couple of these to have in the shop and thoroughly test them out, but I believe they are a very good way to go.

My advise is to get a GY6 12 volt regulator rectifier (just google it) they are very cheap. And then abandon the old 5 or 4 pole regulator/rectifier that you have.

To feed AC into this I would take the red-yellow coils and ground the red wire either at the stator plate or at the junction box by connecting it to a grounded wire (use the screws for the flywheel cover to fasten a ground strap and run a wire into the junction box). Then run the yellow into the GY6 input. And ground the correct tab on the GY6 unit. There are four tabs on the unit. So far you have connected two of them. The remaining tabs are one for regulated DC and one for regulated DC. It's that easy. You simply connect regulated DC to your fuse/battery and perhaps don't even connect the regulated AC to anything.

Then the other wire coming out of the stator should be Purple and it usually power the headlight on AC.. this one still would need regulation. I reccomend a clipper diode (MSR voltage regulator) behind the headlight for this. The purple wire powers the headlight. This way the headlight won't go dim when you use the turn signals or brake pedal. And yes you will need this even with a halogen bulb. Unregulated power from a stator can reach 30 volts or more if it is unregulated - this would blow any bulb.

But with the GY6 and MSR working together it should all be very do-able with minimal modifications to the wiring harness.

For even brighter lights though you may want to run ALL coils in series and feed the power into the GY6 regulator and then tap then run the wire from the headlight (purple) down to the AC tab on the GY6 regulator. This puts all the coils working together for maximum power, but at idle you may get a dim headlight when you have your foot on the brake. To do this you would have to reroute the purple wire that goes to the motor and instead have it head over to the GY6 regulator. You would also need to get out a soldering iron and solder the stator - conecting the end of the purple coil to where the red wire comes out, and then grounding the yellow wire where it comes out of the coil.

I'm actually already running one of those rectifiers! $8 on ebay vs. $125 for a mercato one. Got things sorted with my old stator....really there wasn't much to sort, I'm basically an idiot. I was going to go through all the hassle of swapping them and was looking at wiring diagrams and realized "hey, I don't have a horn. Looks like the ground runs through the horn...I wonder". I hooked it up after cutting the wires to the horn and hard connecting them. Took a couple of tries but I got the headlamp to work, now I need to sort it. It only comes on if I hold the horn button down!

What source did you use for the $8 rectifier? I need to put an order in for a few. I sent and email to a place in texas yesterday but have not heard back. They offered about 6 similar kinds. I just wanted to make sure I got the right one although I'm pretty sure they are universal and any of them would work. But some were $8 and other were $20 and they looked the same. I'm not sure if the $20 ones are more robust or not. And since I have run motors that rev to about 9500 rpm and put out crazy voltages I want to be sure I get a robust one.

Of course I could always protect a cheap one with a MSR clipper diode so that the unit never saw more than 14 volts AC. that's prolly what i will do anyways - just to make sure it's bullet proof.

Here you go Mike. This is the one I used. Bike fired right up. I am having a couple issues now with my left turn signals not wanting to work and my taillight just went out too but I think all of that is related to grounds and isn't due to the rectifier. I say that because my right turn signals work flawlessly. My bike is a total basketcase too....P125 frame with a P200 swap in it....doubting the PO modified the electrical correctly. At some point (probably when I get my GL working and done) I'm gonna strip the P200 down for a respray and my front disk conversion. At that point I'll swap in a new battery less harness probably and turn the cowl into a second glovebox or something....moar storage.